As methods of performing film formation to a substrate, e.g., a semiconductor wafer (hereinafter referred to as a “wafer”), there are known a chemical vapor deposition (CVD) method in which a wafer is disposed within a processing vessel kept in a vacuum atmosphere and a deposit is deposited on the wafer by allowing a reaction gas to react on the surface of the wafer, and an atomic layer deposition (ALD) method or a multi-layer deposition (MLD) method (hereinafter generically referred to as an ALD method) in which a deposit is deposited on a wafer by sequentially supplying plural kinds of mutually-reacting reaction gases to the wafer and allowing the reaction gases to be adsorbed onto the surface of the wafer.
Among film formation devices which perform these film formation processes, there is a single-wafer-type film formation device configured to perform a film formation process by mounting a workpiece wafer on a mounting stand one by one. In the single-wafer-type film formation device, the height position of the mounting stand may be moved up and down depending on the operation contents (e.g., the film formation process or the delivery of the wafer to and from an external transfer mechanism). At this time, from the viewpoint of dust prevention within a processing vessel, there may be a case where an elevator mechanism for the mounting stand is disposed outside the processing vessel. The mounting stand is connected to the elevator mechanism by an elevating shaft which protrudes out of the processing vessel through a through-hole formed in the processing vessel. A stretchable bellows is installed between an edge portion of the through-hole and the elevator mechanism, thereby keeping the processing vessel airtight and maintaining the interior of the processing vessel under a vacuum atmosphere.
If the through-hole is formed so as to have, e.g., a diameter which is approximately a dozen mm to several tens mm larger than the diameter of the elevating shaft, it is possible to avoid contact between components such as the elevating shaft and the processing vessel body. This facilitates assembly and maintenance. On the other hand, if a gap between the elevating shaft and the through-hole is large, a reaction gas may enter the interior of the bellows from the processing vessel. Thus, a reaction product tends to be deposited on the inner surface of the bellows. The bellows is deformed pursuant to the expansion and contraction thereof. At this time, if the reaction product is peeled off and particles are generated, there is a possibility that the particles become a contamination source of a wafer.
In this regard, for example, Patent document 1 discloses a film formation device which includes a substrate holding table configured to hold a substrate to be processed as a film formation target so that the substrate can rotationally move about a vertical axis and can move up and down. This film formation device has a configuration in which a space through which a rotating shaft connected to the substrate holding table moves up and down is sealed by a partition wall such as a bellows or the like. However, Patent Document 1 fails to disclose a detailed configuration of a partition wall that isolates the internal space of the processing vessel and the internal space of the bellows while keeping the substrate holding table rotationally movable and vertically movable.